Got unlimited text messaging but no IM on your phone? The Hackszine weblog steps through how you can set up and use AIM over SMS. The instructions in the post cover the iPhone (which is notoriously lacking a chat application), but the same basic steps should work with any phone. The tutorial shows how you can sign on to AIM by texting your username and password to 265000, then send messages to your buddies. It's not the best solution (it's going to be less instantaneous that IM), and this method isn't entirely new, but if you've got unlimited text messages but no data plan or chat application, it's a cool workaround.